Hello!

Themed Arena and Ranked Arena or even the Training Arena matches players around the whole entire Region. So if your server is already Cross-Server then that's the reason why. Also, Arenas doesn't have a personal level and power but an Arena Setting Levels of 100 only. Thank you.

Hmm.

Player's BP isn't the factor to consider in Arena since all of the players in Arena are given a stats and level of 100. The initiative is the only factor being accounted for in that Arena.